This invention relates to an improved conveying apparatus for conveying a series of die-cut blanks from a rotary die cutter to a blank stacking device.
Rotary die cutters are commonly used to die-cut blanks out of paper or corrugated board stock. These blanks are then stacked for shipping and storage, and are then assembled into containers or the like at some time prior to use. In the past, conveyor systems which have been used to transport die-cut blanks from a rotary die cutter to a blank stacking device have suffered from certain disadvantages.
For example, one approach of the prior art has been to utilize a sandwich belt which takes up blanks as they leave the die cutter. This sandwich belt is vibrated to shake loose scrap, and it operates to drop die-cut blanks onto a conveyor belt which in turn conveys the blanks to a blank stacking apparatus. In such prior art conveyor systems, blanks will often skew, either while on the vibrating sandwich belt, while in the transition between the sandwich belt and the conveyor belt, while on the conveyor belt, or as they leave the conveyor belt and enter the stacking apparatus. Closely spaced side guides can help to align blanks in these prior art conveyor systems; however, closely spaced side guides can also serve to jam a skewed blank.
In order to reduce the problem of skewed and jammed blanks in the conveyor systems of the prior art, it is common practice to operate the entire die cutting operation at a relatively slow speed. While this approach does serve to alleviate the problem of skewed and jammed blanks, it can materially decrease the output of a rotary die cutter. In one system of the prior art, a die cutter designed to operate at a maximum rate of 10,000 blanks per hour was often operated at the much slower rate of 4,000 blanks per hour in order to reduce jamming of blanks in the conveyor system. Such slow speed operation results in severe underutilization of the die cutter.